T30 metallic noise when starting then rough idle The car is a 2005 with auto trans and the QR25DE motor.
I have replaced the head gasket and resurfaced on this motor as a result of overheating due to thermostat failure and now it has a noise similar to a starter motor bad mesh on start up. The motor runs rough for a few seconds then settles down to a nice idle. But after the motor has warmed up it has a unsettled idle and when revved it returns to 1500 rpm where it hangs for a couple of seconds then returns to normal rpm but the rough idle remains. Occasionally when the car has been run for a while it will idle extremely rough.
I have since replaced the timing chain tensioner thinking this may be the cause of the noise on start up but with no improvement.
It is as if there is a timing issue at start up.
I have also replaced the cam sensor and now wondering if it may be a crank sensor even the oxygen sensor as there is a continual light coloured vapor from the exhaust but is not there if the oxy sensor is disconnected.
Any thoughts on this would be welcome